package com.kylin.type3;

public class SingletonTest03 {
    public static void main(String[] args) {
        Singleton instance1 = Singleton.getInstance();
        Singleton instance2 = Singleton.getInstance();
        System.out.println(instance1 == instance2);
        System.out.println("instance1.hashCode=" + instance1.hashCode());
        System.out.println("instance2.hashCode=" + instance2.hashCode());
    }
}

//懒汉式(线程不安全)
class Singleton {

    private static Singleton instance;

    private Singleton() {
    }

    //当调用getInstance，才会创建单例对象，饿汉式
    //提供一个静态的公有方法，当使用到该方法时，才会创建instance 懒汉式
    public static Singleton getInstance() {
        if (instance == null) {
            instance = new Singleton();
        }
        return instance;
    }

}